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[jira] [Comment Edited] (HBASE-12295) Prevent block eviction under us if reads are in progress from the BBs

Date

Wed, 15 Jul 2015 15:30:06 GMT

[ https://issues.apache.org/jira/browse/HBASE-12295?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14628237#comment-14628237
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Anoop Sam John edited comment on HBASE-12295 at 7/15/15 3:29 PM:
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The new method hasTags to go in where? In read path we will deal with Cell type and we can
add this to Cell interface.
May be we can avoid 2 impls one with out tags and one with. Have a state (boolean) in Cell
impl. We have SizeCachedKeyValue abd SizeCachedNoTagsKeyValue now. May be we will only have
SizeCachedKeyValue and it will have a boolean state whether it has tags or not. The getTagsLength()
can check this state ad return 0 or decode tags length. We have extra 6 bytes per cell in
this SizeCachedKeyValue now. Make it 7 is ok IMO
was (Author: anoop.hbase):
The new method hasTags to go in where? In read path we will deal with Cell type and we can
add this to Cell interface.
May be we can avoid 2 impls one with out tags and one with. Have a state (boolean) in Cell
impl. We have SizeCachedKeyValue abd SizeCachedNoTagsKeyValue now. May be we will only have
SizeCachedKeyValue and it will have a boolean state whether it has tags or not. The getTagsLength()
can check this state ad return 0 or decode tags length. We have extra 6 bytes per cell in
this SizeCachedKeyValue now. Make it 7 is ok?
> Prevent block eviction under us if reads are in progress from the BBs
> ---------------------------------------------------------------------
>
> Key: HBASE-12295
> URL: https://issues.apache.org/jira/browse/HBASE-12295
> Project: HBase
> Issue Type: Sub-task
> Components: regionserver, Scanners
> Reporter: ramkrishna.s.vasudevan
> Assignee: ramkrishna.s.vasudevan
> Fix For: 2.0.0
>
> Attachments: HBASE-12295.pdf, HBASE-12295_1.patch, HBASE-12295_1.pdf, HBASE-12295_10.patch,
HBASE-12295_12.patch, HBASE-12295_14.patch, HBASE-12295_2.patch, HBASE-12295_4.patch, HBASE-12295_4.pdf,
HBASE-12295_5.pdf, HBASE-12295_9.patch, HBASE-12295_trunk.patch
>
>
> While we try to serve the reads from the BBs directly from the block cache, we need to
ensure that the blocks does not get evicted under us while reading. This JIRA is to discuss
and implement a strategy for the same.
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